1. Field of the Invention
The invention generally relates to a chip structure and a fabrication method thereof, in particular, to a light-emitting diode (LED) chip structure and a fabrication method thereof.
2. Description of Related Art
A light-emitting diode (LED) is a semiconductor element. The material for forming a light-emitting chip of the LED mainly employs a compound of III-V group chemical elements, for example, gallium phosphide (GaP), gallium nitride (GaN), or gallium arsenide (GaAs). The light-emitting principle of the LED is converting electric energy into optical energy. Specifically, a current is applied to a compound semiconductor of the LED, so as to release energy in the form of light through the combination of electrons and electron holes. Since the light-emitting phenomenon of the LED is not caused by heating or discharging, the service life of the LED is more than 100,000 hours. In addition, the LED has advantages such as fast response, small volume, low power consumption, low pollution, high reliability, and applicability to mass production. Therefore, the application of the LED is very broad and includes, for example, light sources of large-scale billboards, traffic lights, cell phones, scanners, light sources of faxes, and flat lighting devices. In recent years, the LED has a developing trend to be main indoor illuminators.
Taking a GaN LED as an example, the GaN LED has different forms of structures, one of which is a mesa-structure GaN LED. In the mesa-structure GaN LED, two electrodes thereof are located on the same side of the mesa-structure GaN LED, and therefore a phenomenon that the current is concentrated in one region is likely to appear, causing problems such as non-uniform light emission and poor heat dissipation efficiency in the mesa-structure GaN LED. Therefore, a vertical type GaN LED is provided in the prior art for solving the problems. However, a fabrication process of the vertical type GaN LED is complex, and a laser lift-off process technology having high technical thresholds is required, thus making the fabrication cost of the vertical type GaN LED high.